1. Field of the Invention
The present invention relates to an electrode pad, a printed circuit board using the electrode pad, and a method of manufacturing a printed circuit board.
2. Description of the Related Art
With the trend for the miniaturization, thinning, high densification, and packetization of electronic products, a fine pattern, miniaturization, and packetization also need to be implemented in a printed circuit board.
In particular, the number of electric input and output terminals of printed circuit boards following the trend for thinning and high densification have been increased.
In order to cope with the increasing trend, a pitch of the terminal gradually follows the trend for a fine pitch.
Therefore, a method of forming a thin layer during a surface treating process of a terminal has been developed.
Recently, a method of only forming a paladium gold (Pd—Au) layer without forming a nickel (Ni) layer on a surface of a terminal has also been developed.
Generally, the case in which an electrode pad on a printed circuit board only uses a pure palladium (Pd) plating layer or a palladium phosphorus (Pd—P) plating layer is common.
However, when the electrode pad on the printed circuit board only uses the pure palladium (Pd) plating layer or the palladium phosphorus (Pd—P) plating layer, problems such as skip plating, voids and excessive plating may occur.
Patent Document 1, disclosed in the following Related Art Documents, relates to a connection terminal, a semiconductor package using the same, and a method of manufacturing the semiconductor package. Patent Document 1 discloses a conductor layer, an electroless nickel plating layer formed on the conductor layer, and a palladium (Pd) plating layer having a purity of 99 mass %, formed on the nickel (Ni) plating layer.
Patent Document 2, disclosed in the following Related Art Documents, relates to a magnetic sensor package. Patent Document 2 discloses an electrode pad that includes a copper (Cu) layer, a palladium phosphorus (Pd—P) layer formed on the copper (Cu) layer, and a gold (Au) layer formed on the palladium phosphorus (Pd—P) layer.